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Ngo River in Gboko, Benue State, Nigeria which serves as a source of water for domestic and agricultural purposes for the agrarian community receives effluent from Dangote Cement factory. Physicochemical analysis of the effluent outfall and water samples collected along 15 km of the river stretch were carried out in dry and wet seasons respectively. The results obtained were compared to FEPA, WHO and NESREA Standards. For effluent outfall, Temperature, TDS, pH, EC, BOD, COD, sulphate and chloride, total hardness, calcium and magnesium, were found to be within the FEPA standards, while TSS, turbidity, and nitrate, were above the standards. Along 15 km study reach, mean temperature range of 32.4oC to 29.0oC, a TSS of 224 mg/l to 218 mg/l, a turbidity of 45 NTU to 42 NTU, and DO of 1.6 mg/l to 1.2 mg/l were obtain during the dry season, while mean temperature range of 36.8oC to 36.6oC, a TSS of 255 mg/l to 252 mg/l, turbidity of 176 NTU to 168 NTU, and DO 2.8 mg/l to 2. 6 mg/l were obtained during the wet seasons. These results were above WHO and NESREA temperature (25oC drinking water), TSS (30 mg/l domestic and 100 mg/l agriculture) water use, 5 NTU turbidity, and 5mg/l to 7.5mg/l DO standards. The effluent is relatively treated and effects such as aquatic depletion in the environment, decreased soil pore size and decreased permeability in the use of the water for irrigation, and water related diseases are not ruled out. [ABSTRACT FROM AUTHOR]

Pollution and health risk assessment models were used to study the effects of effluents discharged into the Inyishi River, Ikeduru LGA, Imo State, Nigeria. The study aims at investigating the environmental health effects of wastewater effluent discharge from the aluminum extrusion company on the Inyishi River. Samples were collected from both the aluminum extrusion company and Inyishi River and analyzed for physicochemical and trace metal parameters. Models adopted for assessment include transfer factor (TF), contamination factor (Cf), pollution load index (PLI), ecological risk factor (Er), water quality index (WQI), hazard quotient (HQ), and hazard index (HI). The results of the study revealed that pH and TH were within the Nigerian Standard for Drinking Water Quality (NSDWQ) and World Health Organization (WHO) standards. EC values at 2235 ± 0.001 and 105 ± 0.03 μS/cm for S3 and S4 respectively were higher than the permissible standards, while the values of EC at 24.04 ± 0.03, 5.26 ± 0.005, and 0.05 ± 0.01 μS/cm respectively for S1, S2, and SR are within the WHO standard. Very high concentration of SO42− was recorded at S3, while low concentration was measured at S2. Mean values of heavy metal ions studied were within NSDWQ and WHO standards for safe drinking water except for Al, Zn, Cd, Fe, and Mn, with the mean values of metal concentrations observed in the order Al > Fe > Zn > Mn > Cd > Cr. Positive linear correlation based on heavy metal contamination was observed for samples S1 and S2 with SR. High TF values were observed in decreasing order Mn > Cd > Cr > Fe > Zn. Similarly, very high CF was observed for Cd and Al while the PLI was generally high for all the samples. Low Er values were observed for all metals except for Cd, with the mean value of Er observed in the decreasing order Cd ˃ Mn ˃ Zn ˃ Cr. The river water sample generally revealed high WQI and was thus categorized as poor quality. HQ and HI values were below unity (< 1), but might pose health risk to children in cases of prolonged dermal adsorption. In conclusion, the quality of the Inyishi River has been negatively impacted by the wastewater effluent from the aluminum extrusion company. Proper treatment of the river water is therefore recommended before use for domestic purposes as prolonged usage of the untreated water might likely pose serious environmental health risks. [ABSTRACT FROM AUTHOR]

Physico-chemical parameters, heavy metals and bacteriological parameters of water samples of Ogun River near Lafenwa slaughterhouse in Abeokuta, Nigeria were assessed for point and non point sources of pollution and health impacts using standard methods. pH at point of discharge (DP) was 5.5, while average pH ranged from 6.37 (downstream) to 7.1 (upstream). Dissolved oxygen (DO) at DP was 0, but ranged from 3.70 mg·L-1 downstream(DS) to 4.75 mg·L-1 upstream(UP), Chemical oxygen demand (COD) and Total dissolved solid(TDS) ranged from 88.33 mg· L-1 to 111.67 mg·L-1 and 93.33 mg·L-1 to 95.0 mg·L-1 for DS and UP respectively. BOD at DP was 6 mg·L-1, but ranged from 3.73 mg·L-1 UP to 5.27 mg·L-1 DS. EC, turbidity, TSS values at point of discharge were 620μScm, 35 and 9.33 respectively, which were all higher than the values obtained UP and DS. Concentrations of Fe and Pb in the water samples were higher than the WHO maximum permissible limits for drinking water. Total coliform count was about 1100 cfu·mL-1 at all sampling points as against the WHO limit of zero. High concentrations for most parameters are an indication of non-point pollution such as open defecation and washing of clothes in the area. [ABSTRACT FROM AUTHOR]

This study assessed the human health risk of exposure to legacy PAHs in the Nwaenebo River sediments that received effluents for over two decades from the Nigeria National Petroleum Corporation (NNPC) petroleum product Depot in Emene, Enugu, Nigeria. The study went further to estimate economic costs of the sediment PAHs pollution based on the human health risk of exposure. The human health risks were determined by estimating carcinogenic and mutagenic risks via Benzo[a]pyrene total potential equivalent (BaP TPE) and mutagenic equivalent quotient (MEQ). The economic costs of the sediment pollution comprised costs due to mortality and those due to morbidity and were estimated using the value of statistical lives (VSLs) and cost of illness (CoI), respectively. The study, with an appropriate selection of sampling points established that the NNPC petroleum Depot was responsible for the Nwaenebo River sediment PAHs pollution with ƩPAHs concentration 14.3-163 mg/kg. The carcinogenic and mutagenic risks varied from 1.3*10^-5 to 4.7*10^-5 and 1.4*10^-5 to 6.0*10^-5 respectively. Based on risk threshold of 10^-6, these risks were high. The long term economic costs of pollution of the sediments by the PAHs were estimated at 60.5 million USD and 0.46 million USD for mortality and morbidity costs, respectively., (Copyright © 2022 Elsevier Ltd. All rights reserved.)